Fiberglass ductboard is typically utilized for constructing air ducts. The fiberglass ductboard arrives at construction sites in four foot by eight foot or eight foot by eight foot panels. Grooves are then cut into the ductboard where the ductboard is to be folded or bent so that the ductboard may be fashioned into box-like air ducts.
Fiberglass ductboard is typically one inch thick and includes an aluminum foil or staple flap layer on the front side. Grooves are often cut in the back side of the fiberglass within 1/16th of an inch of the foil layer, or right down to the foil layer without a piercing of the foil.